// Press Shift twice to open the Search Everywhere dialog and type `show whitespaces`,
// then press Enter. You can now see whitespace characters in your code.
public class Main {
    public static void main(String[] args) {
        MobileTelephone m=new MobileTelephone();
        SIM s1 =new SIMOFChianMobile();
        m.useSIM(s1);
        m.print();


        SIM s2=new SIMOfChinaUnicom();
        m.useSIM(s2);
        m.print();
    }
}